|Strut and wall interference on jet-induced ground effects of a STOVL aircraft in hover - Kristy, Michael H|
A small scale ground effect test rig was used to study the ground plane flow field generated by a STOVL aircraft in hover. The objective of the research was to support NASA-Ames Research Center planning for the Large Scale Powered Model (LSPM) test for the ARPA-sponsored ASTOVL program. Specifically, small scale oil flow visualization studies were conducted to make a relative assessment of the aerodynamic interference of a proposed strut configuration and a wall configuration on the ground plane...
Keywords: TIME DEPENDENCE; SYSTEM FAILURES; SYSTEMS ANALYSIS; KNOWLEDGE BASED SYSTEMS; SYSTEMS HEALTH MONITORING; SYSTEMS ENGINEERING; SYSTEMS SIMULATION
|Shocks in Dense Clouds in the Vela Supernova Remnant: FUSE - Nichols, Jo|
We have obtained 8 LWRS FUSE spectra to study a recently identified interaction of the Vela supernova remnant with a dense cloud region along its western edge. The goal is to quantify the temperature, ionization, density, and abundance characteristics associated with this shock/dense cloud interface by means of UV absorption line studies. Our detection of high-velocity absorption line C I at 90 to 130 km/s with IUE toward a narrow region interior to the Vela SNR strongly suggests the Vela supern...
Keywords: DEFECTS; DETECTION; FALSE ALARMS; VIBRATION; SYSTEMS HEALTH MONITORING; ALGORITHMS; COST EFFECTIVENESS; FAILURE; TRANSMISSIONS (MACHINE ELEMENTS)
|Decomposition-Based Decision Making for Aerospace Vehicle Design - Borer, Nicholas K.|
Most practical engineering systems design problems have multiple and conflicting objectives. Furthermore, the satisfactory attainment level for each objective ( requirement ) is likely uncertain early in the design process. Systems with long design cycle times will exhibit more of this uncertainty throughout the design process. This is further complicated if the system is expected to perform for a relatively long period of time, as now it will need to grow as new requirements are identified and ...
Keywords: PIEZOELECTRIC GAGES; STRUCTURAL ANALYSIS; CRYOGENIC EQUIPMENT; SYSTEMS HEALTH MONITORING; IMPEDANCE; LOW TEMPERATURE TESTS
|Information Theoretic Approaches to Rapid Discovery of Relationships in Large Climate Data Sets - Knuth, Kevin H.|
Mutual information as the asymptotic Bayesian measure of independence is an excellent starting point for investigating the existence of possible relationships among climate-relevant variables in large data sets, As mutual information is a nonlinear function of of its arguments, it is not beholden to the assumption of a linear relationship between the variables in question and can reveal features missed in linear correlation analyses...
Keywords: AEROSPACE VEHICLES; SYSTEMS HEALTH MONITORING; SENSORS; DEVELOPMENT; FIBER OPTICS; ULTRASONICS; REMOTE SENSING
|Oxygen: Not Just for Breathing Anymore - Yentzen, Michael J|
A brief discussion of the modern oxygen industry is presented. The journey from the past one hundred years to today's oxygen production industry involved such diverse subjects as the Paris theater, the brewing industry, explosives, and the ASTM Committee G-4.
Keywords: HANDBOOKS; TOPEX; POSEIDON SATELLITE; RADIO ALTIMETERS; SPACECRAFT INSTRUMENTS; COMMANDS; TELEMETRY; DISPLAY DEVICES; SYSTEMS HEALTH MONITORING
|Functionalization of Carbon Nanotubes - NON|
Method and system for functionalizing a collection of carbon nanotubes (CNTs). A selected precursor gas (e.g., H2, or F2, or CnHm) is irradiated to provide a cold plasma of selected target particles, such as atomic H or F, in a first chamber. The target particles are directed toward an array of CNTs located in a second chamber while suppressing transport of ultraviolet radiation to the second chamber...
Keywords: SYSTEMS ANALYSIS; SYSTEMS ENGINEERING; PERFORMANCE TESTS; SYSTEMS INTEGRATION; SYSTEMS HEALTH MONITORING; ELECTRIC POWER; SENSORS; SOFTWARE DEVELOPMENT TOOLS; FAULT DETECTION
|Formation Flying Satellite Control Around the L2 Sun-Earth Libration Point - Hamilton, Nicholas H.|
This paper discusses the development of a linear control algorithm for formations in the vicinity of the L2 sun-Earth libration point. The development of a simplified extended Kalman filter is included as well. Simulations are created for the analysis of the stationkeeping and various formation maneuvers of the Stellar Imager mission. The simulations provide tracking error, estimation error, and control effort results...
Keywords: DESIGN ANALYSIS; UNIX (OPERATING SYSTEM); KERNEL FUNCTIONS; SIMULATION; STABILITY; SYSTEMS HEALTH MONITORING; AVIONICS; PROTOTYPES; RANDOM ACCESS MEMORY; RATES (PER TIME)
|MAGNESIUM AND CALCIUM IONS IN THE EARTH'S UPPER ATMOSPHERE - ISTOMIN, V. G|
PRESENTED ARE THE RESULTS OBTAINED FROM THE LAUNCHING OF A GEOPHYSICAL ROCKET IN JUNE 1960, USING A RADIO-FREQUENCY MASS SPECTROMETER SEVERAL TIMES MORE SENSITIVE THAN HAD PREVIOUSLY BEEN USED IN SIMILAR RUSSIAN EXPERIMENTS. MORE THAN 100 SPECTRA WERE OBTAINED AT ALTITUDES FROM 92 TO 206 KILOMETERS, FIVE OF WHICH HAD PEAKS WITH MASS NUMBERS M = 24 TO M = 26. AT AN ALTITUDE OF 103.5 KILOMETERS A PEAK WITH M = 40 WAS OBSERVED.
Keywords: COMPUTER PROGRAMS; SYSTEMS HEALTH MONITORING; COSTS; HANDBOOKS; SOFTWARE RELIABILITY; QUALITY CONTROL; SOFTWARE ENGINEERING; SOFTWARE REUSE; COMPUTER SYSTEMS PERFORMANCE; RELIABILITY ANALYSIS
|Auctioning Airport Slots - Gruyer, Nicolas|
The current allocation of slots on congested European airports constitutes an obstacle to the effective liberalisation of air transportation undertaken in Europe. With a view to favouring effluent slot utilisation and competition, as is the goal of the Euopean commission, we propose to use a market mechanism, based on temporary'' utilisation licences. In order to allocate those licences, we propose and describe an iterated combinatorial auction mechanism where a percentage of licences would be r...
Keywords: APOPTOSIS; AUTONOMY; AUTONOMIC NERVOUS SYSTEM; ARTIFICIAL INTELLIGENCE; BIONICS; DESTRUCTION; SYSTEMS HEALTH MONITORING; CELLS (BIOLOGY); CONTROL SYSTEMS DESIGN
|Quadratic Optimization in the Problems of Active Control of Sound - Loncaric, J.|
We analyze the problem of suppressing the unwanted component of a time-harmonic acoustic field (noise) on a predetermined region of interest. The suppression is rendered by active means, i.e., by introducing the additional acoustic sources called controls that generate the appropriate anti-sound. Previously, we have obtained general solutions for active controls in both continuous and discrete formulations of the problem...
Keywords: AEROSPACE SYSTEMS; MANUFACTURING; MONTE CARLO METHOD; AEROSPACE VEHICLES; FAILURE ANALYSIS; VIBRATION MEASUREMENT; ROTATION; SYSTEMS HEALTH MONITORING; FALSE ALARMS; FAILURE; VIBRATION
|A LEAST ABSOLUTE SHRINKAGE AND SELECTION OPERATOR (LASSO) FOR NONLINEAR SYSTEM IDENTIFICATION - Kukreja, Sunil L.|
Identification of parametric nonlinear models involves estimating unknown parameters and detecting its underlying structure. Structure computation is concerned with selecting a subset of parameters to give a parsimonious description of the system which may afford greater insight into the functionality of the system or a simpler controller design. In this study, a least absolute shrinkage and selection operator (LASSO) technique is investigated for computing efficient model descriptions of nonlin...
Keywords: ROTARY WING AIRCRAFT; SYSTEMS HEALTH MONITORING; TRANSMISSIONS (MACHINE ELEMENTS); DATA BASES; VIBRATION; ENVIRONMENT EFFECTS; ACOUSTIC EMISSION; CRITICAL LOADING; MULTISENSOR FUSION
|Aerospace Safety Advisory Panel - NON|
This report covers the activities of the Aerospace Safety Advisory Panel (ASAP) for calendar year 1998-a year of sharp contrasts and significant successes at NASA. The year opened with the announcement of large workforce cutbacks. The slip in the schedule for launching the International Space Station (ISS) created a five-month hiatus in Space Shuttle launches. This slack period ended with the successful and highly publicized launch of the STS-95 mission...
Keywords: HELICOPTERS; DIRICHLET PROBLEM; DATA REDUCTION; ACCELEROMETERS; SIGNAL PROCESSING; FAILURE; SYSTEMS HEALTH MONITORING; ALGORITHMS; BAYES THEOREM; VECTOR QUANTIZATION; ERROR ANALYSIS
|Thermal Conductivity and Stability of HfO2-Y2O3 and La2Zr2O7 Evaluated for 1650 C Thermal/Environmental Barrier Coating Applications - Zhu, Dong-Ming|
HfO2-Y2O3 and La2Zr2O7 are candidate thermal and environmental barrier coating (T/EBC) materials for gas turbine ceramic matrix composite (CMC) combustor applications because of their relatively low thermal conductivity and high temperature capability. In this paper, thermal conductivity and high temperature stability of hot-pressed and plasma sprayed specimens with representative partially-stabilized and fully-cubic HfO2-Y2O3 compositions and La2Zr2O7 were evaluated at temperatures up to 1700 C...
Keywords: ACOUSTIC EMISSION; NOISE (SOUND); AEROSPACE VEHICLES; ALGORITHMS; SYSTEMS HEALTH MONITORING; PIEZOELECTRICITY; MATHEMATICAL MODELS; SIGNAL PROCESSING; DETECTION; WAVE PROPAGATION; BIOMIMETICS; WIRELESS COMMUNICATION; REAL TIME OPERATION; FINITE ELEMENT METHOD
|Results and current status of the NPARC alliance validation effort - Towne, Charles E.|
The NPARC Alliance is a partnership between the NASA Lewis Research Center (LeRC) and the USAF Arnold Engineering Development Center (AEDC) dedicated to the establishment of a national CFD capability, centered on the NPARC Navier-Stokes computer program. The three main tasks of the Alliance are user support, code development, and validation. The present paper is a status report on the validation effort...
Keywords: ARC JET ENGINES; SPACECRAFT POWER SUPPLIES; ELECTRIC PROPULSION; SPACE PLATFORMS; SPACECRAFT PROPULSION; SYSTEMS HEALTH MONITORING; HYDRAZINES; SPACE COMMERCIALIZATION; SPACE SHUTTLE PAYLOADS; SPACEBORNE EXPERIMENTS
|Computational analysis of the flowfield of a two-dimensional ejector nozzle - Choi, Y. H.|
A time-iterative full Navier-Stokes code, PARC, is used to analyze the flowfield of a two-dimensional ejector nozzle system. A parametric study was performed for two controlling parameters, duct to nozzle area ratio and nozzle pressure ratio. Results show that there is an optimum area ratio for the efficient pumping of secondary flow. At high area ratios, a freestream flow passes directly through the mixing duct without giving adequate pumping...
Keywords: ARCHITECTURE (COMPUTERS); CHEMICAL PROPULSION; CONTROL SYSTEMS DESIGN; PROPULSION SYSTEM CONFIGURATIONS; PROPULSION SYSTEM PERFORMANCE; INSPECTION; MAINTENANCE; REUSABLE ROCKET ENGINES; SYSTEMS HEALTH MONITORING
|Continuation of the Development of Far Infrared Detection Techniques - NON|
A 4 x 32 Ge:Ga detector module for use at wavelengths between 50 and 120 micron has been successfully developed by the MIPS Team at the University of Arizona. With 128 elements, this is the largest focal plane array operating in this wavelength range. This array makes use of recently developed low temperature readouts that operate with low noise and good DC stability at temperatures as low as 2 K. We have measured bare multiplexer read noises of 37 e at 4 K for these parts...
Keywords: SYSTEMS HEALTH MONITORING; LIFE CYCLE COSTS; PAYLOADS; MANAGEMENT SYSTEMS; FLIGHT INSTRUMENTS; SPACECRAFT INSTRUMENTS; HANDBOOKS; FAULT DETECTION; COMPUTER PROGRAMS; SYSTEMS ENGINEERING; COMPONENT RELIABILITY
|A Comprehensive Reliability Methodology for Assessing Risk of Reusing Failed Hardware Without Corrective Actions with and Without Redundancy - Putcha, Chandra S.|
This paper deals with the development of a reliability methodology to assess the consequences of using hardware, without failure analysis or corrective action, that has previously demonstrated that it did not perform per specification. The subject of this paper arose from the need to provide a detailed probabilistic analysis to calculate the change in probability of failures with respect to the base or non-failed hardware...
Keywords: APPLICATIONS PROGRAMS (COMPUTERS); INTERNETS; ARCHITECTURE (COMPUTERS); SCIENTIFIC VISUALIZATION; GROUND STATIONS; REMOTE CONTROL; DIGITAL COMMAND SYSTEMS; SYSTEMS ENGINEERING; SYSTEMS HEALTH MONITORING; COSTS; PERSONAL COMPUTERS; SPACECRAFT MAINTENANCE
|Dayside Proton Aurora: Comparisons between Global MHD Simulations and Image Observations - Berchem, J.|
The IMAGE mission provides a unique opportunity to evaluate the accuracy of current global models of the solar wind interaction with the Earth's magnetosphere. In particular, images of proton auroras from the Far Ultraviolet Instrument (FUV) onboard the IMAGE spacecraft are well suited to support investigations of the response of the Earth's magnetosphere to interplanetary disturbances. Accordingly, we have modeled two events that occurred on June 8 and July 28, 2000, using plasma and magnetic f...
Keywords: SYSTEMS HEALTH MONITORING; NONDESTRUCTIVE TESTS; ALLOYS; DEFORMATION; STRAIN DISTRIBUTION; CENTRIFUGAL FORCE; NOTCHES; CRACKING (FRACTURING); ROTATING DISKS; ROTOR DYNAMICS; DETECTION; VIBRATION TESTS; FINITE ELEMENT METHOD; CENTER OF MASS; DISPLACEMENT
|Cool Software for Hot Materials - NON|
Deformation Control Technology, Inc. (DCT) used a NASA SBIR contract to develop a computer modeling system for evaluating thermal barrier coatings (TBCs) beforehand. Traditional tests of TBCs required Burner Rig tests, which involved the actual application of a coating to a surface. DCT's software reduces experimentation costs as well as led to a breakthrough in understanding the role of bond coat oxidization...
Keywords: SYSTEMS HEALTH MONITORING; AEROSPACE SAFETY; MANAGEMENT SYSTEMS; TECHNOLOGY ASSESSMENT; X-37 VEHICLE; APPLICATIONS PROGRAMS (COMPUTERS); PILOTLESS AIRCRAFT; SYSTEMS INTEGRATION; REUSABLE LAUNCH VEHICLES; REAL TIME OPERATION
|Non-linear boundary-layer receptivity due to distributed surface roughness - Amer, Tahani Reffe|
The process by which a laminar boundary layer internalizes the external disturbances in the form of instability waves is known as boundary-layer receptivity. The objective of the present research was to determine the effect of acoustic excitation on boundary-layer receptivity for a flat plate with distributed variable-amplitude surface roughness through measurements with a hot-wire probe. Tollmien-Schlichting mode shapes due to surface roughness receptivity have also been determined, analyzed, a...
Keywords: ENGINE MONITORING INSTRUMENTS; PROPULSION SYSTEM PERFORMANCE; FAULT DETECTION; MACHINE LEARNING; NEURAL NETS; ROCKET ENGINES; SYSTEMS HEALTH MONITORING; ARCHITECTURE (COMPUTERS); DATA COMPRESSION; ERROR ANALYSIS
|Weight and the Future of Space Flight Hardware Cost Modeling - Prince, Frank A|
Weight has been used as the primary input variable for cost estimating almost as long as there have been parametric cost models. While there are good reasons for using weight, serious limitations exist. These limitations have been addressed by multi-variable equations and trend analysis in models such as NAFCOM, PRICE, and SEER; however, these models have not be able to address the significant time lags that can occur between the development of similar space flight hardware systems...
Keywords: GEAR TEETH; MULTISENSOR FUSION; FATIGUE TESTS; DECISION MAKING; PITTING; SENSORS; WEAR; SYSTEMS HEALTH MONITORING; SPIRAL BEVEL GEARS; SYSTEMS INTEGRATION; VIBRATION MEASUREMENT; OILS; DAMAGE; ALGORITHMS; FUZZY SYSTEMS
|Inferences on Coronal Magnetic Fields from SOHO UVCS Observations - Poletto, G.|
The characteristics of the magnetic field ubiquitously permeating the coronal plasma are still largely unknown. In this paper we analyze some aspects of coronal physics, related to the magnetic field behavior, which forthcoming SOHO UVCS observations can help better understand. To this end, three coronal structures will be examined: streamers, coronal mass ejections (CME's) and coronal holes. As to streamers and CME's, we show, via simulations of the Ly-alpha and white light emission from these ...
Keywords: GEARS; NASA PROGRAMS; HELICOPTERS; SYSTEMS HEALTH MONITORING; CRACK PROPAGATION; TRANSMISSIONS (MACHINE ELEMENTS); RESEARCH; DESIGN ANALYSIS; GEAR TEETH; NOISE REDUCTION; LUBRICANTS; THERMAL ANALYSIS
|Aerospace Medicine and Biology: A Continuing Bibliography with Indexes - NON|
This report lists reports, articles and other documents recently announced in the NASA STI Database.
Keywords: SYSTEMS HEALTH MONITORING; SPACECRAFT MAINTENANCE; REAL TIME OPERATION; SIGNAL PROCESSING; CHECKOUT; EXPERT SYSTEMS; SENSORS; REUSABLE LAUNCH VEHICLES; ROCKET TEST FACILITIES; MODULES
|Model Atmosphere Analyses of Ultraviolet Spectra of Novae in Outburst - Starrfield, Sumne|
We discuss the physical effects that are important for the formation of the early spectra of novae. Nova atmospheres are optically thick, fast expanding shells with flat density profiles, leading to geometrically very extended atmospheres. We show that the properties of early nova spectra can be understood in terms of this basic model and discuss some important effects that influence the structure and the emitted spectrum of nova atmospheres, e.g., line blanketing, NLTE effects, and the velocity...
Keywords: SYSTEMS HEALTH MONITORING; FAILURE MODES; REDUNDANCY; APPLICATIONS PROGRAMS (COMPUTERS); COMPUTER SYSTEMS PROGRAMS; SYSTEMS MANAGEMENT; SYSTEMS ANALYSIS; MANAGEMENT ANALYSIS; GASEOUS DIFFUSION; COMPUTER SYSTEMS DESIGN; ASSESSMENTS; SYSTEMS INTEGRATION; FAULT TOLERANCE
|Observed Land Impacts on Clouds, Water Vapor, and Rainfall at Continental Scales - Jin, Menglin|
How do the continents affect large-scale hydrological cycles How important can one continent be to the climate system To address these questions, 4-years of National Aeronautics and Space Administration (NASA) Terra Moderate Resolution Imaging Spectroradiometer (MODIS) observations, Tropical Rainfall Measuring Mission (TRMM) observations, and the Global Precipitation Climatology Project (GPCP) global precipitation analysis, were used to assess the land impacts on clouds, rainfall, and water vapo...
Keywords: PROPULSION SYSTEM CONFIGURATIONS; SMART STRUCTURES; PROPULSION SYSTEM PERFORMANCE; SAFETY; SYSTEMS HEALTH MONITORING; ENGINE MONITORING INSTRUMENTS; LIFE (DURABILITY); LIFE CYCLE COSTS; COMPONENT RELIABILITY; AIRCRAFT PERFORMANCE
|The Future of Bio-technology - Trent, Jonatha|
Hosts of technologies, most notably in electronics, have been on the path of miniaturization for decades and in 2005 they have crossed the threshold of the nano-scale. Crossing the nano-scale threshold is a milestone in miniaturization, setting impressive new standards for component-packing densities. It also brings technology to a scale at which quantum effects and fault tolerance play significant roles and approaches the feasible physical limit form many conventional ''top-down'' manufacturing...
Keywords: NONINTRUSIVE MEASUREMENT; FAULT DETECTION; CONTRAROTATING PROPELLERS; RAMAN SPECTRA; PREFLIGHT OPERATIONS; PILOTLESS AIRCRAFT; INSPECTION; SYSTEMS HEALTH MONITORING; LAUNCH VEHICLES; TEAMS; SWARMING; SPECTROPHOTOMETERS
|Exploring Martian Impact Craters: Why They are Important for the Search for Life - Schwenzer, S. P.|
Fluvial features and evidence for aqueous alteration indicate that Mars was wet, at least partially and/or periodically, in the Noachian. Also, impact cratering appears to have been the dominant geological process  during that epoch. Thus, investigation of Noachian craters will further our understanding of this geologic process, its effects on the water-bearing Martian crust, and any life that may have been present at the time...
Keywords: AEROSPACE VEHICLES; ARCHITECTURE (COMPUTERS); EMBEDDED COMPUTER SYSTEMS; DATA ACQUISITION; PANELS; COMPUTERIZED SIMULATION; ALGORITHMS; ALUMINUM; ROBOTICS; SYSTEMS HEALTH MONITORING; NONDESTRUCTIVE TESTS; SENSORS; AVIONICS; PIEZOELECTRIC TRANSDUCERS; INSPECTION; COMPUTER PROGRAMS
|A Decade of X-Vehicles: Lessons Learned - McNeal, Curtis I., Jr|
The paper discusses the following: Collect lessons learned from successful and unsuccessful X-vehicle programs conducted by DoD and NASA during the 1990s. Evaluate data to determine broad/cross cutting reasons for success. Propose guidelines that will promote successful future NASA X-vehicle program.
Keywords: AUTOMATIC CONTROL; SYSTEMS ANALYSIS; DATA BASES; COST ANALYSIS; ARTIFICIAL INTELLIGENCE; ARCHITECTURE (COMPUTERS); SYSTEMS ENGINEERING; SYSTEMS HEALTH MONITORING; BANDWIDTH; SENSORS; HEURISTIC METHODS; DECISION MAKING
|Development of an agility assessment module for preliminary fighter design - Ngan, Angelen|
A FORTRAN computer program is presented to perform agility analysis on fighter aircraft configurations. This code is one of the modules of the NASA Ames ACSYNT (AirCraft SYNThesis) design code. The background of the agility research in the aircraft industry and a survey of a few agility metrics are discussed. The methodology, techniques, and models developed for the code are presented. FORTRAN programs were developed for two specific metrics, CCT (Combat Cycle Time) and PM (Pointing Margin), as ...
Keywords: FAILURE ANALYSIS; SPACE SHUTTLE MAIN ENGINE; FAULT DETECTION; FAULT DETECTION; MACHINE LEARNING; ROCKET ENGINES; SYSTEMS HEALTH MONITORING; ENGINE MONITORING INSTRUMENTS; IDENTIFYING; KNOWLEDGE BASED SYSTEMS
|Knowledge Navigation for Virtual Vehicles - Gomez, Julian E|
A virtual vehicle is a digital model of the knowledge surrounding a potentially real vehicle. Knowledge consists not only of the tangible information, such as CAD, but also what is known about the knowledge - its metadata. This paper is an overview of technologies relevant to building a virtual vehicle, and an assessment of how to bring those technologies together.
Keywords: TURBOFAN ENGINES; EXHAUST GASES; GAS TEMPERATURE; SYSTEMS HEALTH MONITORING; ENGINE CONTROL; OPTIMAL CONTROL; LINEAR PARAMETER-VARYING CONTROL; NEURAL NETS; DETERIORATION; FEEDFORWARD CONTROL; LIAPUNOV FUNCTIONS
|Gas Jets - Chaplygin, S|
A brief summary of the contents of this paper is presented here. In part I the differential equations of the problem of a gas flow in two dimensions is derived and the particular integrals by which the problem on jets is solved are given. Use is made of the same independent variables as Molenbroek used, but it is found to be more suitable to consider other functions. The stream function and velocity potential corresponding to the problem are given in the form of series...
Keywords: AIRCRAFT ENGINES; AMPLITUDES; TORSIONAL VIBRATION; ACCELEROMETERS; CRACKS; AIRCRAFT SAFETY; SYSTEMS HEALTH MONITORING; CIVIL AVIATION; PROPULSION SYSTEM PERFORMANCE; SYSTEMS ENGINEERING; DETECTION; FAULT TOLERANCE; STRESS INTENSITY FACTORS
|Temporal Evolution of Nanostructures in a Model Nickel-Base Superalloy: Experiments and Simulations - Sudbrack, Chantal K.|
The temporal evolution of the nanostructure of a model Ni-base superalloy (Ni-5.2 at.% Al-14.2 at.% Cr) is studied experimentally employing three-dimensional atom-probe (3DAP) microscopy in conjunction with kinetic Monte Carlo (KMC) simulations at 600 C. It is demonstrated that not only can the mean compositions of individual gamma' (Ni3Al with the Li2 structure) precipitates be measured but the Ni, Al, and Cr concentration profiles within the precipitates can also be determined for precipitates...
Keywords: MULTISENSOR FUSION; ACCELEROMETERS; MICROELECTROMECHANICAL SYSTEMS; OPERATING COSTS; SYSTEMS HEALTH MONITORING; DATA MANAGEMENT; DATA ACQUISITION; DATA SYSTEMS; TRANSDUCERS; CALIBRATING; COST REDUCTION; LIFE CYCLE COSTS
|Waste collection subsystem study - NON|
Practical ways were explored of improving waste compaction and of providing rapid turnaround between flights at essentially no cost for the space shuttle waste collection subsystem commode. Because of the possible application of a fully developed shuttle commode to the space station, means of providing waste treatment without overboard venting were also considered. Three basic schemes for compaction and rapid turnaround, each fully capable of meeting the objectives, were explored in sufficient d...
Keywords: ORBIT TRANSFER VEHICLES; SYSTEMS HEALTH MONITORING; PROPULSION SYSTEM PERFORMANCE; REUSABLE ROCKET ENGINES; SPACE BASES; TURBOROCKET ENGINES; MAINTENANCE; PRODUCT DEVELOPMENT; PROPULSIVE EFFICIENCY; SPACE STATIONS
|Aeroacoustics of Supersonic Elliptic Jets - Khavaran, Abbas|
The sound field due to a supersonic elliptic jet is studied by direct integration of the propagation equations. Aerodynamic predictions are based on numerical solution to the compressible Navier-Stokes equations in conservative law form, with a k-epsilon turbulence model. In the high frequency limit, the sound field is described by eigenrays that link the source of noise to an observer in the far-field...
Keywords: ENGINE MONITORING INSTRUMENTS; ENGINE TESTS; EXPERT SYSTEMS; FAULT DETECTION; GROUND TESTS; SYSTEMS HEALTH MONITORING; ANOMALIES; REAL TIME OPERATION; SPACE SHUTTLE MAIN ENGINE
|Agent-Based Chemical Plume Tracing Using Fluid Dynamics - Zarzhitsky, Dimitri|
This paper presents a rigorous evaluation of a novel, distributed chemical plume tracing algorithm. The algorithm is a combination of the best aspects of the two most popular predecessors for this task. Furthermore, it is based on solid, formal principles from the field of fluid mechanics. The algorithm is applied by a network of mobile sensing agents (e.g., robots or micro-air vehicles) that sense the ambient fluid velocity and chemical concentration, and calculate derivatives...
Keywords: AVIONICS; REAL TIME OPERATION; SPACECREWS; MODULARITY; FAILURE; AEROSPACE VEHICLES; SYSTEMS INTEGRATION; ARTIFICIAL INTELLIGENCE; AEROSPACE ENGINEERING; SYSTEMS HEALTH MONITORING; COST REDUCTION; SYSTEM FAILURES; HUMAN-COMPUTER INTERFACE; MISSION PLANNING
|Atmospheric Models for Mars Aerocapture - Justus, C. G.|
level Mars atmospheric model. Applications include systems design, performance analysis, and operations planning for aerobraking, entry descent and landing, and aerocapture. Typical Mars aerocapture periapsis altitudes (for systems with rigid- aeroshell heat shields) are about 50 km. This altitude is above the 0-40 km height range covered by Mars Global Surveyor Thermal Emission Spectrometer (TES) nadir observations...
Keywords: ALGORITHMS; DATA BASES; SPACE SHUTTLE MAIN ENGINE; REAL TIME OPERATION; PROGRAM VERIFICATION (COMPUTERS); COMPUTERIZED SIMULATION; SYSTEMS HEALTH MONITORING; FAULT DETECTION; SPACE EXPLORATION; SYSTEMS INTEGRATION; SENSORS
|NASA/ASEE Summer Faculty Fellowship Program. 1994 research reports - NON|
This document is a collection of technical reports on research conducted by the participants in the 1994 NASA/ASEE Summer Faculty Fellowship Program at Kennedy Space Center (KSC). This was the tenth year that a NASA/ASEE program has been conducted at KSC. The 1994 program was administered by the University of Central Florida in cooperation with KSC. The program was operated under the auspices of the American Society for Engineering Education (ASEE) with sponsorship and funding from the Office of...
Keywords: CONTROL SYSTEMS DESIGN; PERFORMANCE PREDICTION; SYSTEMS HEALTH MONITORING; FAULT DETECTION; HELICOPTER ENGINES; ON-LINE SYSTEMS; REAL TIME OPERATION; TURBOSHAFTS; ALGORITHMS; COMPUTERIZED SIMULATION; ERROR ANALYSIS
|The F-18 High Alpha Research Vehicle (HARV) parameter identification flight test maneuvers for optimal input design validation and lateral control - Morelli, Eugene A|
Flight tests maneuvers are specified for the F-18 Alpha Research Vehicle (HARV). The maneuvers were designed for open loop parameter identification purposes, specifically for optimal input design validation at 5 degrees angle of attack, identification of individual strake effectiveness at 40 and 50 degrees angle of attack, and study of lateral dynamics and lateral control effectiveness at 40 and 50 degrees angle of attack...
Keywords: ANOMALIES; ENGINE MONITORING INSTRUMENTS; SPACE SHUTTLE MAIN ENGINE; STRAIN GAGES; FEASIBILITY; NEURAL NETS; STATISTICAL ANALYSIS; STRUCTURAL VIBRATION; SYSTEMS HEALTH MONITORING; TURBINE PUMPS; ACCELEROMETERS; APPLICATIONS PROGRAMS (COMPUTERS)
|A Plasmoid Thruster for Space Propulsion - Koelfgen, Syri J.|
There are a number of possible advantages to using accelerated plasmoids for in-space propulsion. A plasmoid is a compact plasma structure with an integral magnetic field. They have been studied extensively in controlled fusion research and are classified according to the relative strength of the poloidal and toroidal magnetic field (B(sub p), and B(sub t), respectively). An object with B(sub p), / B(sub t) much greater than 1 is classified as a Field Reversed Configuration (FRC); if B(sub p) ap...
Keywords: X-33 REUSABLE LAUNCH VEHICLE; BRAGG GRATINGS; SYSTEMS HEALTH MONITORING; MANAGEMENT SYSTEMS; SYSTEMS INTEGRATION; FLIGHT TESTS; F-18 AIRCRAFT; COMMUNICATION EQUIPMENT; DATA TRANSMISSION; FIBER OPTICS
|The Eclipse Project - Tucker, To|
The Eclipse Project by Tom Tucker provides a readable narrative and a number of documents that record an important flight research effort at NASA's Dryden Flight Research Center. Carried out by Kelly Space and Technology, Inc., in partnership with the Air Force and Dryden at Edwards Air Force Base in the Mojave Desert of California, this project tested and gathered data about a potential newer and less expensive way to launch satellites into space...
Keywords: SYSTEMS HEALTH MONITORING; UH-60A HELICOPTER; COMPLEX SYSTEMS; HELICOPTER DESIGN; REAL TIME OPERATION; RESEARCH AIRCRAFT; ANALOG TO DIGITAL CONVERTERS; FLIGHT TESTS
|Cryogenic Carbonate Formation on Mars: Clues from Stable Isotope Variations Seen in Experimental Studies - Socki, Richard A.|
Discoveries of large deposits of sedimentary materials on the planet Mars by landers and orbiters have confirmed the widely held hypothesis that water has played a crucial role in the development of the martian surface. Recent studies have indicated that both water ice and liquid water may have been present and in the case of water ice perhaps is still present on or near the surface of Mars. However, there remains much controversy about the prevailing atmospheric conditions and climate of Mars d...
Keywords: REVERBERATION CHAMBERS; LOADS (FORCES); STANDARD DEVIATION; ANTENNA DESIGN; SYSTEMS INTEGRATION; AVIONICS; MAGNETIC PERMEABILITY; RADIATION MEASUREMENT; ELECTROMAGNETIC RADIATION; SYSTEMS HEALTH MONITORING; DATA FLOW ANALYSIS; FREQUENCY RANGES; INPUT/OUTPUT ROUTINES
|Use of Piloted Simulation for High-Angle-of-Attack Agility Research and Design Criteria Development - Ogburn, Marilyn E.|
The use of piloted simulation at Langley Research Center as part of the NASA High-Angle-of-Attack Technology Program (HATP) to provide methods and concepts for the design of advanced fighter aircraft is discussed. A major focus is to develop the design process required to fully exploit the benefits from advanced control concepts for high-angle-of attack agility.
Keywords: CERAMIC COATINGS; DELAMINATING; SYSTEMS HEALTH MONITORING; TEMPERATURE DEPENDENCE; LUMINESCENCE; EMISSION SPECTRA; TEMPERATURE GRADIENTS; OXIDES; THERMAL CONTROL COATINGS; PROBES; OPTICAL PROPERTIES; PHOSPHORS; THERMOGRAPHY; TRANSLUCENCE; REFLECTANCE
|Analysis of Effective Thermal Conductivities of Honeycomb-Core and Corrugated-Core Sandwich Panels - Swann, Robert T.|
Equations are derived for the transfer of heat in sandwich panels. An exact method i s developed for considering internal reflections of radiant heat and for reducing the given problem to an equivalent problem which may be solved by well-established black-body methods. Temperature distributions and effective thermal conductivities are calculated for both honeycomb-core and corrugated-core sandwich panels...
Keywords: ADAPTIVE CONTROL; PRESSURE RATIO; ENGINE TESTS; TEMPERATURE RATIO; GAS TURBINE ENGINES; LIFE (DURABILITY); MULTIVARIABLE CONTROL; DEGRADATION; THRUST; FEASIBILITY ANALYSIS; PROPULSION SYSTEM PERFORMANCE; SYSTEMS HEALTH MONITORING
|Near-Optimal Re-Entry Trajectories for Reusable Launch Vehicles - Chou, H.-C.|
A near-optimal guidance law for the descent trajectory for earth orbit re-entry of a fully reusable single-stage-to-orbit pure rocket launch vehicle is derived. A methodology is developed to investigate using both bank angle and altitude as control variables and selecting parameters that maximize various performance functions. The method is based on the energy-state model of the aircraft equations of motion...
Keywords: SIGNAL ANALYSIS; DYNAMIC TESTS; ENGINE TESTS; FLIGHT TESTS; NONLINEAR SYSTEMS; MAPPING; ENGINE FAILURE; EXPERT SYSTEMS; SYSTEMS HEALTH MONITORING; ENGINE ANALYZERS; SPACE SHUTTLES; SIGNATURE ANALYSIS; ANOMALIES; SIGNAL PROCESSING; DETECTION
|The SWIFT Gamma-Ray Burst X-Ray Telescope - Hill, J. E.|
The Swift Gamma-Ray Burst Explorer is designed to make prompt multi-wavelength observations of Gamma-Ray Bursts and GRB afterglows. The X-ray Telescope enables Swift to determine GRB positions with a few arcseconds accuracy within 100 seconds of the burst onset. The XRT utilizes a mirror set built for JET-X and an XMM-Newton/ EPIC MOS CCD detector to provide a sensitive broad-band (0.2-10 keV) X-ray imager with an effective area of more than 120 sq cm at 1.5 keV, a field of view of 23.6 x 23.6 a...
Keywords: SYSTEMS INTEGRATION; FAULT DETECTION; ARCHITECTURE (COMPUTERS); TRANSDUCERS; ROCKET ENGINES; MULTISENSOR FUSION; SYSTEMS HEALTH MONITORING; SENSORS; ARTIFICIAL INTELLIGENCE; COMPUTER COMPONENTS; AIRBORNE/SPACEBORNE COMPUTERS; PROGRAM VERIFICATION (COMPUTERS); DATA STRUCTURES; NEURAL NETS
|Failure of Anisotropic Unstructured Mesh Adaption Based on Multidimensional Residual Minimization - Wood, William A.|
An automated anisotropic unstructured mesh adaptation strategy is proposed, implemented, and assessed for the discretization of viscous flows. The adaption criteria is based upon the minimization of the residual fluctuations of a multidimensional upwind viscous flow solver. For scalar advection, this adaption strategy has been shown to use fewer grid points than gradient based adaption, naturally aligning mesh edges with discontinuities and characteristic lines...
Keywords: SYSTEMS HEALTH MONITORING; DATA ACQUISITION; SYSTEMS INTEGRATION; SYSTEMS ENGINEERING; COMMAND AND CONTROL; RADIO FREQUENCIES; WIRELESS COMMUNICATION; EXPERT SYSTEMS; FLIGHT TESTS; COMPUTER PROGRAMS; COMPUTER PROGRAMMING; ARCHITECTURE (COMPUTERS); LANDING GEAR; COMPONENT RELIABILITY; COMPUTER SYSTEMS DESIGN; FAULT DETECTION; AIRCRAFT PARTS
|Simulation of Physical Experiments in Immersive Virtual Environments - Noor, Ahmed K.|
An object-oriented event-driven immersive Virtual environment is described for the creation of virtual labs (VLs) for simulating physical experiments. Discussion focuses on a number of aspects of the VLs, including interface devices, software objects, and various applications. The VLs interface with output devices, including immersive stereoscopic screed(s) and stereo speakers; and a variety of input devices, including body tracking (head and hands), haptic gloves, wand, joystick, mouse, microph...
Keywords: SYSTEMS HEALTH MONITORING; WIRELESS COMMUNICATION; DESIGN ANALYSIS; PARAMETERIZATION; APPLICATIONS PROGRAMS (COMPUTERS); DATA STORAGE; AIRCRAFT EQUIPMENT; LIFE (DURABILITY); FAULT DETECTION; SYSTEMS ENGINEERING; DATA ACQUISITION; COMMAND AND CONTROL; ARCHITECTURE (COMPUTERS); FLIGHT TESTS
|A method for exploiting redundancy to accommodate actuator limits in multivariable systems - Litt, Jonathan|
This paper introduces a new method for accommodating actuator saturation in a multivariable system with actuator redundancy. Actuator saturation can cause significant deterioration in control system performance because unmet demand may result in sluggish transients and oscillations in response to setpoint changes. To help compensate for this problem, a technique has been developed which takes advantage of redundancy in multivariable systems to redistribute the unmet control demand over the remai...
Keywords: BEAM INTERACTIONS; ION EMISSION; ION SOURCES; MASS FLOW RATE; NEUTRAL PARTICLES; PLUMES; CHARGE TRANSFER; ION ENGINES; PLASMA INTERACTIONS; PROPULSION SYSTEM PERFORMANCE; SPECTROSCOPIC ANALYSIS; SYSTEMS HEALTH MONITORING; ARGON; ELECTRON SCATTERING
|HISPASAT launch and early operations phases: Computation and monitoring of geostationary satellite positioning - Brousse, Pascal|
Since 1974, CNES, the French National Space Agency, has been involved in the geostationary launch and early operations phases (LEOP) of moving satellites from a transfer orbit delivered by a launcher to a geostationary point. During the operations and their preparation, the Flight Dynamics Center (FDC), part of CNES LEOP facilities, is in charge of the space mechanics aspects. What is noteworthy about the Spanish HISPASAT satellite positioning is that all the operations were performed on the cus...
Keywords: DEEP SPACE NETWORK; AUTONOMY; COMMAND AND CONTROL; DATA ACQUISITION; PAYLOADS; RADIO FREQUENCIES; SCHEDULING; SYSTEMS HEALTH MONITORING; FLIGHT OPERATIONS; GROUND BASED CONTROL; RADIO TELESCOPES; SATELLITE TRACKING; SPACEBORNE TELESCOPES; TRACKING STATIONS; U.S.S.R. SPACE PROGRAM; VERY LONG BASE INTERFEROMETRY
|Effects of Aircraft On Aerosol Abundance in the Upper Troposphere - Ferry, G. V.|
A significant increase in sulfuric acid aerosol concentration was detected above 10 km pressure altitude during a cross-corridor flight out of Shannon on October 23, 1997. The source of this aerosol is ascribed to commercial aircraft operations in flight corridors above 10 km, because (1) a stable atmosphere prevented vertical air mass exchanges and thus eliminated surface sources, (2) air mass back trajectories documented the absence of remote continental sources, and (3) temperature profiler d...
Keywords: FLOW MEASUREMENT; FLOWMETERS; THREE DIMENSIONAL MODELS; APPLICATIONS PROGRAMS (COMPUTERS); HYDROCARBON COMBUSTION; REMOTE SENSING; GEOGRAPHIC INFORMATION SYSTEMS; COMPUTATIONAL FLUID DYNAMICS; REUSABLE LAUNCH VEHICLES; SYSTEMS HEALTH MONITORING; EXHAUST FLOW SIMULATION; FLAME SPECTROSCOPY; FLOOD PREDICTIONS; HYDROLOGY MODELS; CRYOGENICS